Question

我试图用java更新我的数据库。我在Netbeans工作，代码中没有错误但仍然没有更新行。

   private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

            try{
               Class.forName("com.mysql.jdbc.Driver").newInstance();
          }
          catch(ClassNotFoundException | InstantiationException | IllegalAccessException e){
              JOptionPane.showMessageDialog(this,"Error in connectivity" );

          }
            try{

               String m11 = jTextField1.getText();
      String m22 = jTextField2.getText();
         com.mysql.jdbc.Connection conn = (com.mysql.jdbc.Connection)DriverManager.getConnection("jdbc:mysql://localhost/inventorysystem","root","root123");
         Statement stmt = conn.createStatement();
         int bp = JOptionPane.showConfirmDialog(this,"Do you want to update the record ?");
         if(bp == JOptionPane.YES_OPTION){
            String query = "update inventorycatalogmap set inventorycatalogname = '"+m11+"' and ProductCatalog='"+m22+"' where inventorycatalogname='"+m11+"';";
        stmt.execute(query);
         JOptionPane.showMessageDialog(this,"Record has been updated");
         }
         if(bp == JOptionPane.CANCEL_OPTION){
             NewFrame2 t = new NewFrame2();
             t.dispose(); 
             t.setVisible(true); 
         }
          if(bp == JOptionPane.NO_OPTION){
             NewFrame2 i = new NewFrame2();
              i.dispose(); 
             i.setVisible(true); 
         }
         stmt.close();
         conn.close();

          }
          catch(SQLException | HeadlessException e){
               JOptionPane.showMessageDialog(null,"Invalid Entry","message",2); 
          }
        }

有人可以建议，我的实施出了什么问题？

Answer 1

你缺少conn.commit（）;

stmt.close();
 conn.commit();
 conn.close();

可能你的连接的自动提交没有设置为真。

Answer 2

你的代码是开放的语法错误和SQL注入，而你必须使用PreparedStatement它更安全，更有帮助：

String query = "update inventorycatalogmap set inventorycatalogname = ?, ProductCatalog=? where inventorycatalogname=?";
try (PreparedStatement update = conn.prepareStatement(query)) {
    update.setString(1, m11);
    update.setString(2, m22);
    update.setString(3, m11);
    update.executeUpdate();
}

您的查询中有错误：

set inventorycatalogname = '" + m11 + "' and ProductCatalog='" + m22 + "' where 
//---------------------------------------^^^

另外，当您设置许多字段时，不应使用and，只需使用,

将它们分开

我试图用java更新我的数据库。我在netbeans工作，代码中没有错误但仍然没有更新行

2 个答案: